Pulverizer mill



Apru- 13, 1926.l 1,580,610

4 A. KELLER PuLvERIzER MILL Filed Jan. 25, 1924 2 sheets-sheet 'z fn ven/or.-

Patented Apr. 13, 1926 UNITED s'rATEs .AUGUST KELLER, or :BEBLIN-LICHTERFELDE, GERMANY.

runvnnrznn MILL Application mea January 25, 1924. serial No. 688,435.

To all whom, z't may concern.'

Be it known that I, AUGUST KELLER, a citizen of Germany, residing at Berlin-Lichterfelde, Germany, have invented certain new and useful Improvements in Pulverizer Mills, of which the following is a specifica tion. X My invention refers to pulverizer mills and more particularly to a millbf "the type in which a number of ballsare kept running in-a circular race-way by means of pushers kept in constant circular motion, the particular object being to improve the efliciency and durability-of such mills.

It is al further object of my invention to avoid as far as possible all friction between the balls and the pushers driving them and, at the same time, to reduce the wear of the balls and pushersy with a Viewy to lengthening the life of these parts.

It is a further object of my iiiventiomto provide means for regulating with great.

nicety the supply of fresh material to the balls.

It is another object of my invention to imas well as of the dustffrom the mill, the rst beine eifected by mechanical means, the last main y pneumatically.

It is still' another object of my invention to provide means for preventing the driving gear of the mill'from breaking in the case where the mill should for some unforeseen reason come to a dead stop.

With these and other objects inv view, my invention consists in the lmprovements more Yfully described hereinafter and disclosed in the drawings annexed to this specification and forming part thereof, the pulverizer mill shown in the drawing by wa of example being fitted with all these improve-- ments.-

1 is the subcylindrical base of the mill, 2 is a conica cover .plate carrying a b earing for the vertical shaft, 3 is a cylindrical standard placed on top of the cover plate and base. 4 is la easingand 5 'is the annular chamber from which the material is evacuated. 6 and 7 are concentric cylindrical 13 is an. annular and 17, respectively and bearing a cog wheel 18 meshing with thelarge cogwheel 19 on the lower part 20 of the vertical operating shaft composed of two separate-parts for the purpose to be disclosed later on. Part 20 of this shaft is located in a ball bearing v.21 mounted on the base 1l and another ball bearing 22 carried by the plate 2.l A disc 23 fixed to the upper part 24 of the vertical shaft .is rotatably supported by balls 25 running in aprace-way 26 fixed to the top portion 27 of the standard 3. On this top' portion rests the grindin ring or race-way 28 holding the rinding alls 299 30 is the yoke fixed to s aft 24 above ring 28 and carrying the downwards extending pushers4 31 and inclined lifting blades 32, an aperture 33 allowing fresh materialtodrop into vthe ring- 28. 34 is a cylindrical )acket mountedon the yoke 30 and 35 is a funnel suspended from the cover plate 9 and extending concentrically with the jacket with its' lower endin close proximity to the yoke 30. The upper end of shaft 24 extends up wards through the aperture 36 of the cover plate 9 and is here supported by another ball earing 37. A pinion 38 keyed onto the projecting end of the shaft meshes with an intermediate gear wheel 39 turning about a 'journal 40 projectingfrom the cover -plate and carryin a smaller wheel 41 meshing with the toot ed rim 42 of the feeding plate 43 rotatably mounted on plate 9. 'A larger wheel 44 driven by wheel 39is keyed onto an' intermediate shaft 45 located in bearings 46, 47 and extending alongside of the outer shell 8. A gear wheel 48 keyed to the lower end of intermediate shaft 45 serves for driving the expeller ring 49 carrying scraper blades 50. Ring 49 restson rollers v51 turning about journals lodged in the outer wall of the chamber 5.

One of the pushers 31 vis shown in Figure 3 in axial section.y In aconical seat 52 of the arm suspended from the yoke 30 a j'ournal 53 is secured by means of a nut 54 and washer 55". 56 is a cap surroundin the projecting portion of journal 53. 5 58 are roller bearings inserted between the parts and taking up radial friction, while a ball bearing constituted by a race-way 549 fixed to the cap 56 and another race-way 60 fixed to the journal with balls inserted between them takes up the axial thrust. The cap is prevented from gliding olf the journal by a ring 61. On the circumference of the cap there is mounted a conicalv sleeve 62 of hardened material highly resistive against abrasion. In cooperating with a grinding ball 29, thecap 56 and conical sleeve 62 act like a roller, revolving in contact with the ball and thereby preventing both the ball and pusher from being worn out, as is the case with the balls and pushers in the pulverizing mills hitherto known, in which the pushers exert a braking effecten the balls, thereby causing not only a great and useless waste of energy, but also necessitating frequent'exchange of both balls and pushers.

The pusher rolls being situated on their journals with the interposition of ball and roller bearings, revolve almost without friction and therefore vnecessitate the least possible expenditure o motive power. In cases where. the mate; ial to be ground enters the mill in heated condition, I provide for an effective cooling of the rollers by means of water circulating within the cap.

.The feeding plate shown more particular- 1y in Figs. 4 and 5 substantially consists of the rotary plate 43 designed to receive the fresh material to be fed into the mill and a scraper 63 disposed in a plane extending f eccentricall across the upper surface of the plate 43 an being adjustable in longitudinal direction, jthe rear end of the scraper 63 projecting from a guide 64 being attached to a sleeve 65 adjustably mounted on a spindle governed by means of a hand wheelr 66. With the plate 43 rotating in the direction of the arrow (Fig. 5?! the material placed thereon, on meeting t e scraper 63, will be thrown oif the plate 43, to drop into a funnel 67 surmountin the aperture 68 which leads into the funne 35 and to the aperture 33 in the yoke 30. According to the length of that portion of the scraper 63 which extends across plate 43, more or less material will be held up b the scraper and be caused to drop off. In t is manner a very exact regulation of the quantity fed into the mill can be obtained. By casting the plate 43' and the 'toothed rim 42 in one piece, the 4constructional height of the feeding plate is kept very low.

-As mentioned above, the vertical main shaft is composed of two parts 20 and' 24. .A

coupnng sleeve 69 is mounted on the upper end of part 20 and firmly connected 'therewith by a key 7 Ol A pin 71 traversing the upper end of sleeve 69 and the lower end of shaft 24 forms the connection between these two parts. However, the shearing strength of this pin is so chosen that,if the upper part of the mill including the pushers and balls should for some reason come to a dead stop, thepin will break or be shorn off and, in thus disengaging the two parts of the vertical shaft, prevent the cog wheels driving the shaft from breaking or getting damage l The above described mill operates as follows The material deposited on the feeding plate 43 is caused by the scraper 63 to drop through the funnel 67 and aperture 68 into the funnel 35 and through aperture 33 into the grinding chamber proper.

The material, after having been pulverized, will be lifted from the zone of operation of the grinding walls by they upwardly moving currents of air due to the action of the fans 32. Carried by these air currents, the heavier and larger particles will be separated by gravity and will fall back into the pulverizing zone and be reground between the 4balls and the grinding rings, while the lighterl material passing with the air currents through the screens 6 and 7 will settle in the annular chamber 5, being expelled therefrom by the -Scrapers 50 which, owing to a suitable gearing interposed between ring 49 and pin1on 38 on the main shaft, revolves only very slowly, thereby preventing the raising of great masses of dust. The comparatively small quantities of iloating particles are removed by suction, a fan 72 eing arranged to act on the exhaust 14, the annular chamber 13 and slots 12 in the lange 10 of cover plate 9.

In contradistinction to pulverizing mills hitherto known, in which rapidly rotating fans operating in an annular chamber similar'to chamber 5 were employed for expelling the ground material, the slowly revolving scraper ring oll'ers the advantage of preventin 'generation of dust escaping through the 'ex aust. On the other hand, the large sectional area of the settling .chamber conined between the shell 8 and the screens 6 and 7 and the provision of narrow exhaust slots.12 evenly distributed all over the circumference of the cover flange 10 allow the air to be drawn from the large annular space in a Y-uniform `manner and with a very low velocity, the air thus escaping freely throu l1 all the meshes of the screens and therey preventing their being clogged. Owing to this slow velocity of the air, the finely ground particles have time to settle and to be caught yA the Scrapers 50. f

All the shafts 15, 20 and 24 being located in ball bearings exclusively, all these bearings being enclosed in dust tight shells,

iso

medew the losses due to friction are minimized and a great saving in motive power is obtained. The advantages offered by providing the pushers with revoluble heads have been fully explained before.

I wish it to be understood that I do not desire to be limited to the exact details of construction shown and described, for obvious modifications will occur to a person skilled in the art.

I claim:

l. In a pulverizing mill, a grinding ring, a grinding ball in said ring, and a pusher member coacting tangentially with said ball and having a constantly shiftingand rolling contact therewith. p

'2. The combination, with va-"pulv'erizer mill, of a grinding ring, a grinding ball in said ring, a shaft, a pusher arm connected with said shaft for circular motion in said ring and a revoluble member connected with said pusher arm and adapted to cooperate with said ball, said revoluble member havinga conical contact face substantially tangential to the surface-of the ball whereby to provide for a minimum frictional contact with the ball and permit free movement of the latter relative to the member. v

3. In a pulverizing mill, a grinding ring, a grinding ball in said ring, a pusher arm, means for actuating said arm, a roller member mounted on said arm coacting tangentially with said ball and having a constantn ly shifting and rolling contact therewith, and friction reducing means inserted between said roller and said pusher arm.

4. In a pulverizing mill, the combination of a shell, a grinding ring therein, a

ring, a revolving unit within said shell composed of a receptacle adapted to receive the' material to be ground and having an opening in the base thereof immediately over the ring and ball to distribute the material thereto, a pusher arm depending from said receptacle having a roller member coacting 'grinding ball adapted to 'travel about said with the ball, said receptacle having an i exterior blade member adapted to impart a lifting action to the pulverized material to propel it to the collecting chamber, and a collecting chamber extending about said shell to receive the pulverized material.

' 5. The combination, with a pulverizer mill, of a vertical main shaft, extending centrally through said mill, a vertical shaft extending alongside of said mill and gearing with said main shaft, an annular chamber, surrounding said main shaft, a ring and Scrapers removably mounted in said chamber, and means on said second shaft for, revolving said ring and Scrapers at low velocity.

(i. The combination, with a. pulverizer mill, of grinding means arranged in the centre of said mill, a screen surrounding the space above said grinding means, means within said space for generating an outwardly directed air current, a shell surrounding said screen in spaced relation thereto, so as to form an outer annular space of large sectional area, a slotted cover at the upper end of said space and suction means adapted to act on said slots.

In testimony whereof I aliix my signature.

AUGUST KELLER. 

